High-frequency tuning unit



July 20, 1948. VAUGHN 2,445,700

HIGH-FREQUENCY TUNING UNIT Filed March 14, 1946 Patented July 20, 1948 ca sson HIGH-reta er TUNIN UNIT Kennet fau l nri e en iis 3 a snor.

a canms io m an Cedar ap; s, loss;

a corporation of. Iowa This invention relates to tuning units for use with radio apparatus and more particularly to a compactly assembled and: mounted unit which is suitable for operation at highradio frequencies.

In so-called slug-tuned radio frequency circuits employing a permeabilitytuned inductance, a padder condenser and a trimmer condenser associated therewith, rough tuning'may be accomplished by adjusting the extent 'of telescoping of the powdered'iron core or' slug into the inductance'co'il Winding, and finer adjustment may be made by tuning'either or both of the condensers. When such devices are'used at high radio frequencies; it is necessary to eliminate long interconnecting leads and sliding contacts or wiping contacts associated with the various components of the tuned circuit.

Accordingly, it is a principal object of this invention to provide a tuning unit suitable for use at high radio frequencies, wherein all of. the components of. the unit are compactly'assembled on a single mount and with short conductors connecting the various components.

It is another object ofv this'invention to provide an improved permeability tuner for useat high radio frequencies'etnd carrying integrally therewith'a padder condenser and an adjustable trinimer condenser, all'compactly arranged on a single mounting. I

Afeature' of the invention relates to a novel assembly of parts which cooperate to" form a compact pluralelectrostatic condenser system for use with a permeability tuner.

A further feature relates to the novel organization, arrangement and interconnection of parts which cooperate to produce an improved permeability tunerfor use at high radio frequencies.

Other objects, features and advantages of this invention will be apparent to those skilled in the art as will be evident from the 'following'des'criptions taken in connection with the'accompanying drawing, in which,

Fig. 1 is a front elevation view of an embodiment of the inventive concept.

Fig. 2 is a top view of Fig. 1.

Fig. 3 is a side view of Fig. 1.

Fig. 4 is an enlarged cross-sectional view of a portion of Fig. 1, taken along line 4-4 of Fi 2.

Fig. 5 is a view of part of Fig. 4.

Fig. 6 is a top view of Fig. 1 with the top cap which forms the rotary plate of the trimmer condenser removed.

Fig. 7 is a bottom view of the button-type condenser shown in edge view in Fig. 4.

Fig. 8 is a top plan view of the button-type. condenser;

Fig. 9 is a top end view of Fig. 5.

Fig. 10 is a schematic diagram of the electric connections of the various components shown in Figs. 1-9.

Referr ng to the drawing, the mounting of the various components comprises an elongated hollow tube I0, to which is fastened at the upper end a circular inverted box-like member H. A rotatable disc l1 lies flat against the outer; flat wall H a of member II. The members I 0, H and I! are made of a low loss ceramic such as customarily used for insulation in high frequency radio circuits. Attached, for example by soldering to electroplated areas on member H), are two metal tabs l3, M to which the Opposite ends of the inductance coil I2 are respectively soldered. As shown in Figs. 1 and 3, the-coil I2 is tightly wound around member 10, and if desired, the surface of member I0 may be helically threaded to receive and space the successive turns of the coil.

Ceramic disc I! is rotated by turning pin l8 which passes freely through wall l in and through metal spider 3|. A metallic coating 20 is provided on the slightly recessed upper face of disc.

l1, and a short metal strap loads soldered at one end to coating '20 and at the other end to the head of pin I8. Coating20 serves as therotor plate of the trimmer condenser 2| and in the particular arrangement shown in Fig. 10 is connected to ground by means of the spider 3i and the lug 31a which extends outwardly through an opening in the member I l.

Plating 20 is semi-circular in area as shown in Fig. 2, and electrostatically cooperates with, a stator plate 22 in the form of a strip metal coating or plating on the upper face of wall Ha, and extending half-way around the margin of. wall Ila asshown in Fig. 6. Plating 22 is connected, to the terminal lug 23 by a stripv of solder 220. on the exterior surface of member I I (Fig. 4) Lug 23 also connects to the central plate 28 of a button-type condenser 24 which is shown in detail in Figs. 7 and 8. This condenser comprises a disc 24a of mica or other suitable insulation through the center region of which passes a metal rivet whose ends are flattened against the mica to form the condenser plates 28. Surrounding the mica disc 24a and rigidly fastened thereto is a metal ring 26 which acts as the other condenser plate in cooperation with plates 28. The lug 23 is soldered to the central plate 28 as shown in Fig. '7. The plate 26 of the button-type condenser has three equally spaced lugs 25 which are adapted to press against the inner surface of member ll, thus centering the button condenser. It should be noted that this condenser is supported by means of the right angled bend in lug member 23 which is soldered to coatin 22a. The horizontal portion of this bend passes through a small opening in member I l as shown more clearly in Fig. 4. The inside surface of member I l is provided with a localized coating 30 of solder so that when member 24 is inserted in place, one of the lugs 25 presses against and makes positive electrical contact with coating 30. This coating 30 also extends down so as to extend across the shouldered lower lip of member ll.

As shown more clearly in Fig. 5, the upper shouldered end of member l likewise carries a coating [6 of solder so that when parts It] and H are fitted together, as shown in Fig. 4, electrical contact is made between coatings I6 and 30. The coating I is provided with a downwardly extending strip [6a to which the connecting lug I4 is soldered. In accordance with one feature of the invention, and as shown in Figs. 5 and 9, the coating 16 does not extend around the entire periphery of member lo, thus avoiding high frequency losses which would otherwise occur by reason of a closed loop of solder. The parts It and II can be rigidly fastened together by flowing molten solder externally around part of the overlapping shoulders of members 10 and H. Terminal [3 is connected to lug 23 by strap-32.

The lower end of member Hl has a portion Illa of reduced diameter which is adapted to pass through a circular opening in a panel or bracket 34. Portion Illa has a peripheral recess to receive a suitable split ring washer 35 whereby the entire unit is locked rigidly to member 34. A suitable magnetic slu or core 33 of compressed powdered magnetic material is suitably mounted for adjustable telescoping movement with relation to member ll) as is well-known in so-called permeability tuners.

The equivalent electrical connections of the two condensers and the coil l2 are shown in Fig. 10 wherein corresponding parts to those of Figs. 1-9 are similarly designated.

While one particular embodiment has been dis-- closed, Various changes and modifications can be made therein without departing from the spirit and scope of the invention.

What is claimed is:

l. A high frequency tuner unit comprising a tubular insulator member, an inductance coil wound around said member, a permeability core mounted for telescoping movement into said tubular member, an inverted cup-shaped member of insulation having'a shouldered lip which seats against a corresponding shoulder on the end of said tubular member, a conductive coating on the outer fiat wall of said cup-shaped member I of said cup-shaped member and electrically connected to said conductive coating, a connector tab making electrical contact with the said shank of said adjusting member and extending outwardly through the peripheral wall of said cupshaped member, and means including said conductive coating to complete an electrical circuit from the other electrode of said button-type condenser to said second-mentioned connector tab.

2. A'tuning and trimmer condenser unit for high frequency tuner assemblies comprising a cup-shaped insulating member, a rotatable insulator disc seated against the external face of the fiat wall of said cup-shaped member, a first coating of conductive material attached to the margin of said flat wall, a second coating of conductive material on the inner surface of said cup-shaped member, a third coating of conductive material on the flat surface of said disc which is out of contact with said first coating and forming therewith a rotary adjustable condenser, a pin having its shank passing centrally through said disc and said fiat wall, the outer end of said pin being electrically connected to said third conductive coating and the inner end of the pin being connected to said second conductive coating, a metal spider carried by the inner end of said pin and in wiping engagement with the lastmentioned conductivecoating, a connector tab connected to said spider and extending outwardly through the peripheral wall of said cup-shaped member, a button-type condenser supported within said cup-shaped member by'means of another connector tab fastened to one electrode of the button-type condenser, said other connector tab extending outwardly through the peripheral wall of said cup-shaped member and anchored thereto, and means connecting the other electrode of said button-type condenser to said second conductive coating.

KENNETH E. VAUGHN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,222,770 Hartl Nov. 26, 1940 2,368,857 McClellan Feb. 6, 1945 

